1. Field of the Invention
The present invention relates to a permanent magnet electrical rotating machine, a wind power generating system, and a method of magnetizing a permanent magnet.
2. Prior Art
The amount of electricity produced by wind power has greatly increased in recent years. There have been increasing demands for permanent magnet-type machines with a large capacity of 1 MW or more to improve the economy by increasing the capacity of a single machine. Although the efficiency of a large-capacity permanent magnet-type machine is high, the value of its loss is large. When the body of an electrical rotating machine is enlarged so as to suppress the heat generation density to a level nearly equal to that of a small-capacity machine, the weight has to be increased and thus the manufacturing cost and construction cost are increased, making it necessary to increase the heat generation density with a small body. However, a high heat generation density requires high cooling performance, resulting in an increase in cost. If the structure does not readily generate heat, the electric characteristics are lowered and it becomes difficult for the permanent magnet electrical rotating machine to meet the requirements of an electric power generator. To achieve high-efficiency cooling at a low cost without the electric characteristics being sacrificed, a structure suitable for being efficiently cooled is necessary.
In the Patent Document 1, heat generation between poles is suppressed by providing a gap between the poles to reduce a magnetic flux leak.
Patent Document 1: Japanese Patent application Laid-open No. 2006-81377